Age of Information: Whittle Index for Scheduling Stochastic Arrivals

Age of information is a new concept that characterizes the freshness of information at end devices. This paper studies the age of information from a scheduling perspective. We consider that a base-station updates many users on stochastic information arrivals over a wireless broadcast network, where only one user can be updated for each time. In this context, we aim at developing a transmission scheduling algorithm for minimizing the long-run average age. To develop a lowcomplexity transmission scheduling algorithm, we apply the Whittle’s framework for restless bandits. We successfully derive the Whittle index in a closed form and establish the indexability, by introducing a post-action age. Based on the Whittle index, we propose a scheduling algorithm, while experimentally showing that it closely approximates an age-optimal scheduling algorithm.